The present invention relates to methods for producing a conjugated Z-alken-yn-yl acetate and an ω-halo-2-alkynal which is an intermediate thereof, particularly to a method for producing Z-13-hexadecen-11-yn-yl acetate which is a sex pheromone component of a pine processionary moth (scientific name: Thaumetopoea pityocampa), which is a forest pest insect in Europe.
A pine processionary moth (scientific name: Thaumetopoea pityocampa) is an insect widely inhabiting European countries such as France, Italy, Spain, Portugal and Greece. It has become a problem as a forest pest insect because of feeding damage to trees such as pine and cedar. In addition, poisonous hair of the larva of this moth is known to cause a serious allergic reaction in humans, livestock, pets and the like. Moreover, in recent years, the habitat of the moth has been expanding northward from the Mediterranean region due to the effect of global warming. There is therefore a demand for the development of a novel control method of the moth.
It has been reported by A. Guerrero et al. in 1981 (A. Guerrero et. al., Tetrahedron Letters, Vol. 22, 2013-2016, 1981) that the sex pheromone component of this pine methodionary moth is Z-13-hexadecen-11-yn-yl acetate having a conjugated Z-alken-yn-yl acetate structure. Development of a control method such as mating disruption or mass trapping using this sex pheromone has therefore been expected.
The methods for producing Z-13-hexadecen-11-yn-yl acetate that have already been reported include: a method reported by F. Camps et al. and making use of an elimination reaction of a secondary tosylate and use of an organolithium compound (Spanish Patent Publication No. 2010719, Spanish Patent Publication No. 8204407, and F. Camps et. al., Chem. Lett., 703, 1981), a method reported by G. Cardillo et al. and using lithium diisopropylamide and a dehydration reaction (G. Cardillo et. al., Gazzetta Chimica Italiana, 112, 231, 1982), a method reported by J. K. Stille et al. and using an acetylene zipper reaction, an organotin compound, and diimide reduction (J. K. Stille et. al., J. Am. Chem. Soc., 1987, 109, 2138), a method reported by M. Gardette et al. and using a reaction between an organocopper lithium reagent and an acetylene compound (M. Gardette et. al., J. Chem. Ecolg., 9, 219, 1983), and a method reported by D. Michelot et al. and using a hydroboration reaction and a coupling reaction in the presence of a palladium catalyst (D. Michelot et. al., J. Chem. Res., 4, 1043, 1982). Thus, in these methods, a special raw material such as an organolithium compound, an organoboron compound, an organotin compound or a diimide compound is used and a step of requiring a low-temperature reaction at −10° C. or less for the production is comprised.
On the other hand, as a method for producing Z-13-hexadecen-11-yn-yl acetate under mild conditions without using a special raw material, there has been reported a production method using a Wittig reaction between 13-tetrahydropyranoxy-2-tridecyn-1-al obtained by protecting an alcohol group at the C13-position with a tetrahydropyranyl group and propylidene triphenylphosphorane (F. Camps et. al., J. Chem. Ecolg., 9, 869, 1983).